Jet question and a few others

[78xs11]

Hi all,
Hope all is well with you all. Heres the story. The P.O. had installed a 4-1 unknown exhaust long ago.Im sure he didnt change anything in the carbs (he was original owner). Well after I recieved the HOGSLAYER I cleaned it up and pulled the carbs and cleaned them up a bit not a TOTAL disassembly, but they were very clean and taken care of. No varnish or heavy crud. Well it ran good, I installed seafoam, balanced the carbs tweaked the mixture screws, all was ok untill the exhaust broke. I just installed a MAC 4-2 side dump last nite. During the test run I noticed a slight lack of arm yanking power. Also when moderately applying the throttle @5-6000rpm there is a bog. If I smoothly apply the gas its ok. Other than that it runs and idles great.
Do I need to change jets? Or will a re balance and mixture tweak fix the problem? Also Where do I put the bracket that keeps the sidestand from hitting on the exhaust when in the up position??... Thanks in advance to all.........DG

[TopCatGr58]

Hey there DG,

You should do a resynch, the old pipes may have had a small leak, and your previous synch may not be right now?! The 4-2 should breath about as well as the 4-1's, but maybe not as well, especially at the higher rpms? But they still flow easier than the OEM's!

At what range is your power loss? The 4-1's are notorious for causing a slight loss in the lower rpms, yet you are saying the newer 4-2's are causing a loss!? Also a bog has developed, again, a possible indication of richness, but rare in the 5-6k range? You say it runs okay when you give throttle slow. Are you sure it's a BOG vs. a drop in power?

You've got the 78, the oldest 11, and it could be the pickup coil wires acting up, depending on how much rotation the timing plate is going thru?? Is your air filter clean, what type do you have?

You'll want to make sure the carbs vacuum slides are also moving freely and easily, and that the ignition system is working right, before changing jets!

When I had put my 4-1's on a few years after I got my bike, I didn't rejet it at all. But after my rebuild and new Intake Pods, I then rejetted!
T.C.

[TopCatGr58]

PS.

DennyZ could use your old 4-1 system!
T.C.

[prometheus578]

"Exhausting"

I just replied to the Aussie about the MAC 4 into 2 system and the centerstand. I didn't use the gizmo that keeps the stand from hitting the exhaust pipe. The pipe is in the way of the arm of the stand, forcing it to hang way low. I put a pipe on the arm and "cautiously" bent the pi$$ out of it so that the centerstand will ride up a little higher. It's out of the way of the pavement when cornering, but can still be seen hangin' under the bike. I'm curious if anyone else has found a more creative solution to this problem.
Oh, to answer your question... No bracket... arm of centerstand is cradling the underside of the pipe.
(I put a MAC 3 into 1 system on my XS850 and had to remove the centerstand completely. I was not happy)

Pipe Dreams, Put that in your pipe and smoke it,
Oh pipe down, Don't have a leg to stand on, etc
(There, T.C., I've used up all the good quips.)

[Ken Talbot]

SWMBO's 'H still has its 4-2 exhaust, but I lowered it so much the centrestand drags if you even think about going around a corner. I just took it off, and now only re-install it for servicing. For the most part, centrestands are highly over rated IMHO....

[motoman]

Hey ther 78xs................try backing out idle mix screws another 1/2 a turn and try it again. Don't know if there's any corrolation, but I have to back out my air screw(there on filter intake side) of my motocrosser when I race at higher elevation to eliminate the same scenario. On our XS's Mikuni's that being on motor side of throttle shafts, it is fuel screw. Backing all of them out another 1/4-1/2 a turn may eliminate the slightly lean condition at any given steady rpm, since idle circuit still comes into play. The transfer to full main circuit suddenly instead of gradually in my opinion causes the stumble cause of too much 'spread' of fuel ratio in idle to main circuit. Realizing my motocross racer is a 2-stroke, same principal as there both just an air compressor, other than the Keihn carb your dealing with an air screw on opposite end of throttle plate, where as the Mikuni your dealing with a fuel screw on front side of throttle plate. Would try that before re-jetting, and double check sync of all four carbs. That's just my opinion, and works for me on the Mikuni's just as it does on the 2-strokes with the Keihn carb.

[78xs11]

Thanks for the replys, Topcat: The range of the powerloss starts @ 5000 rpm thru @ 6000 rpm. If I feather it thru that range its ok. Dosent really matter what gear. Its real smooth untill that point then..yuck.....I repaired two wires at the pickup coil previously.The other two check out good. Im under the impression that I should have smooth power thru redline. Would a mis-adjusted float or 2 cause these symptoms? I didnt do those yet.....my bad.
Other than that it starts great, Idles good with a VERY slight rpm burp. Factory air box and clean filter.
PROM and KEN: Im refering to my side stand not a centerstand. My bike didnt come with a centerstand. The only thing I see it good for is some maintenence procedures........I really want to FEEL THE POWER SMOOTHLY on this beast...Thanks DG

[TopCatGr58]

Hey DG,

Hate to say it, but there's a chance your repair may have gone bad, has happened before!! Guy ruled out that problem because he had "fixed" it before. Went thru all kinds of heck trying to figure it out. Finally reinspected his PU wires, they were re-broken! Did the repair again and all was well!! I'd revisit your repair! With it acting up in ALL Gears, sounds more suspicious than carbs right now!


Okay, Prom, I'll offer up the Peace Pipe!!
T.C.

[78xs11]

UPDATE:::: I pulled the carb bank again for another run thru ( 3rd times a charm!!)
Well heres the results,,,,,,,Average heights of the floats are @ 26-27mm. one side higher than the other on every carb......Also #1 carb had a leaky float, (there was some sloshing in the one float).
I took the valve seat and screen assy out and found yuck in there too, not enough to clog the screen, but enough to make me think I didnt clean them out as I should have before. "Triple clean" words to live by........Im going searching for info here, but once I find the leak in the float, How do I drain out whats in there before the repair??? This site rules... Thanks again DG